package.json

{
  "name": "paraswap-trade-examples",
  "version": "1.0.0",
  "main": "index.js",
  "license": "MIT",
  "dependencies": {
    "bignumber.js": "^9.0.1",
    "paraswap": "^4.1.2",
    "web3": "^1.3.5"
  }
}

paraswap_trade.js

const {ParaSwap} = require("paraswap");
const BN = require("bignumber.js");
const Web3 = require("web3");

const PROVIDER_URL = process.env.PROVIDER_URL;
const USER_ADDRESS = process.env.USER_ADDRESS;
const referrer = "chucknorris";
const SLIPPAGE = 1;//1%

const networks = {
  MAINNET: 1,
  POLYGON: 137
}

const tokens = {
  [networks.MAINNET]: [
    {
      "decimals": 18,
      "symbol": "ETH",
      "address": "0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE"
    },
    {
      "decimals": 6,
      "symbol": "USDC",
      "address": "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48"
    },
    {
      "decimals": 18,
      "symbol": "DAI",
      "address": "0x6B175474E89094C44Da98b954EedeAC495271d0F"
    }
  ],
  [networks.POLYGON]: [
    {
      "decimals": 18,
      "symbol": "MATIC",
      "address": "0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE"
    },
    {
      "decimals": 8,
      "symbol": "WBTC",
      "address": "0x1bfd67037b42cf73acf2047067bd4f2c47d9bfd6"
    }
  ]
}

function t(symbol, network) {
  network = network || networks.MAINNET;

  return tokens[network].find(t => t.symbol === symbol);
}

class ParaSwapper {
  constructor(network){
    this.web3Provider = new Web3(PROVIDER_URL);

    this.paraSwap = new ParaSwap(network);
  }

  async getRate(from, to, amount) {
      return this.paraSwap.getRate(from.address, to.address, amount, 'SELL', {referrer}, from.decimals, to.decimals);
  }

  async buildSwap(from, to, srcAmount, minAmount, priceRoute) {
      return this.paraSwap.buildTx(from.address, to.address, srcAmount, minAmount, priceRoute, USER_ADDRESS, referrer);
  }
}

async function swap(_srcAmount, from, to, network) {
  try {
    const srcAmount = new BN(_srcAmount).times(10 ** from.decimals).toFixed(0);

    const ps = new ParaSwapper(network);

    const priceRoute = await ps.getRate(from, to, srcAmount);

    const minAmount = new BN(priceRoute.destAmount).times(1 - SLIPPAGE / 100).toFixed(0);

    const transaction = await ps.buildSwap(from, to, srcAmount, minAmount, priceRoute);

    console.log("transaction", transaction);


  } catch (error) {
    console.error(error);
  }
}

/*
swap(
  1, 
  t("ETH", networks.MAINNET), 
  t("DAI", networks.MAINNET),
  networks.MAINNET
);
*/

swap(
  1, 
  t("MATIC", networks.POLYGON), 
  t("WBTC", networks.POLYGON),
  networks.POLYGON
);